Simulation of the inner electrode geometry effect on the rundown phase characteristics of a coaxial plasma accelerator



Título del documento: Simulation of the inner electrode geometry effect on the rundown phase characteristics of a coaxial plasma accelerator
Revue: Revista mexicana de física
Base de datos: PERIÓDICA
Número de sistema: 000447026
ISSN: 0035-001X
Autores: 1
1
1
Instituciones: 1Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Querétaro. México
Año:
Periodo: Ene-Feb
Volumen: 67
Número: 1
Paginación: 162-172
País: México
Idioma: Inglés
Tipo de documento: Artículo
Enfoque: Analítico, teórico
Resumen en inglés A 2D computational model, incorporating the Snowplow approximation in the mass balance, is used to simulate the acceleration of an annular current sheath along two coaxial electrodes, with the inner one having either cylindrical or conical shape. The circuit, mass and momentum equations are simultaneously solved in 2D (r,z) considering initial breakdown along the insulator surface, ideal gas mass accretion by the current sheath (snowplow model) and distributed inductance along a coaxial transmission line short-circuited by the current sheath. Plasma density and electron temperature in the current sheath are estimated using standard planar shock theory. Numerical integration of the model’s equations for a given electrode geometry yields the temporal evolution of the current sheath parameters during the axial acceleration phase. In order to see the effect of the inner electrode shape on sheath parameters (i.e. transit time, kinetic energy, total mass, shape, etc.) and/or circuit properties (i.e. circuit inductance, voltage and current evolution, etc.), the portion of the inner electrode beyond the insulator was given a conical shape. By changing the cone slant in a range between ±5o, it was found that the current driven on the plasma sheath varies nonlinearly with the angle. The divergent (positive angle) electrode gives the sheath the highest kinetic energy, being twice the value corresponding to that of the straight inner electrode case, and the transit time is reduced from 1.34 to 1.20 μs. The estimates of plasma density and electron temperature indicate that the achievable ion densities are on the order of 4 x 1022 m-3, which corresponds to 30 % ionization, and typical temperatures at the end of the rundown phase are on the order of 8 eV. These values are comparable with those measured in experimental devices. The development of this tool will enable us to benchmark its results against an experimental installation currently close to being operationa
Disciplinas: Física y astronomía
Palabras clave: Física de materia condensada,
Simulación de plasma,
Aceleradores de plasma,
Modelo de Snowplow
Keyword: Condensed matter physics,
Plasma simulation,
Plasma accelerators,
Snowplow-model
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